I was heading towards the dawnguard, and noticed a dragon insignia on the map that I haven't found yet. So I traveled there (Lost Tongue Overlook) and killed the dragon and as soon as I struck the final blow I got a misc. quest to "Return to Esbern". I went to see him and the only dialogue that shows is about Parthanax and killing him...nothing new, I'm confused? Any help is appreciated

Masterfryman